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BIOLOGY 

LIBRARY 

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AN  UNDESCRIBED  ACRANIATE:  ASYMMETRON 
LUCAYANUM.  By  E.  A.  ANDREWS.  With  Plates  XIII 
and  XIV. 

While  the  Johns  Hopkins  Marine  Station  was  located  at  Alice 
Town,  North  Bernini,  Bahamas,  in  June  and  July,  1892,  a  small 
amphioxus  or  lancelet  came  under  observation  and  was  at  once 
recognized  as  quite  different  from  those  commonly  known. 

Owing  to  the  very  great  morphological  interest  attached  to  our 
knowledge  of.  the  acraniate  vertebrates,  this  new  member  of  the 
group  has  been  studied  and  compared  with  the  known  lancelets 
to  determine  to  what  extent  it  adds  to  the  present  conception  of 
acraniate  anatomy.  The  result,  as  presented  in  the  present  article, 
is  that  this  Bahama  lancelet  is  generically  distinct,  though  morpho- 
logically but  little  removed  from  the  others  in  the  main  features 
that  make  the  acraniates  isolated  from  all  higher  forms. 

Before  stating  what  are  these  generic  characters  the  habits  and 
habitat  of  the  living  animal,  as  far  as  known,  may  serve  as  a  hint 
of  the  possible  explanation  of  some  of  those  anatomical  peculiarities. 

Examination  of  the  very  strong  current  that  passes  out  from  the 
lagoon  to  the  Gulf-stream  between  North  and  South  Bernini  fre- 
quently resulted  in  the  capture  of  large  numbers  of  these  small 
lancelets.  They  were  taken  in  the  tow-net  while  swimming  at  or 
near  the  surface;  most  abundantly  at  the  early  part  of  the  ebb-tide 
when  it  had  been  high  tide  about  nine  o'clock  in  the  evening; 
rarely  in  the  daytime  or  late  at  night  or  on  the  rising  tide.  They 
were  also  obtained  buried  in  the  sand-flats  that  furnish  the  charac- 
teristic fauna  of  this  ebb-tide  current,  but  only  a  few  could  be  found 
here  and  there  at  the  western  end  of  Stokes  Cay  and  also  half  a 
mile  to  the  east  of  East  Point,  East  Wells.  They  may,  however, 
be  much  more  abundant  in  these  flats  than  would  appear  from  the 
above  statement,  since  their  small  size  and  the  soft  permeable 
nature  of  the  purely  calcareous  sand  would  make  their  detection 
much  more  difficult  than  it  would  be  for  such  large  lancelets  as 
Branchiostoma  caribceum  which  we  had  taken  in  great  numbers  in 
the  firm  continental  sands  of  Tampa  Bay,  Florida. 

213 


427212 


;  •• ';  '-,:-'  '•  -::     :  -V-  .    •  '  BIOLO<3\ 

'  E.' A.  ANDREWS. 

The  specimens  taken  in  June  were  larger,  often  sexually  mature, 
while  those  taken  later  were  generally  immature  or  larval  forms. 

In  captivity  they  live  like  the  European  lancelet ;  occasionally 
leaving  the  sand  and  swimming  about  with  considerable  velocity, 
but  soon  falling  to  the  bottom  and  resting  upon  one  side  as  if  ex- 
hausted or  else  burrowing  instantly  into  the  sand  within  which  they 
move  about  with  great  celerity.  As  long  as  the  water  be  pure  they 
rarely  leave  the  sand  in  the  daytime  and  then  quickly  return  when 
stimulated  to  motion  by  a  slight  touch  or  jar. 

In  flat  glass  dishes  without  sand  they  arrange  themselves  with 
reference  to  light  in  a  manner  suggesting  that  we  have  here  amongst 
these  simple,  eyeless  vertebrates  an  example  of  heliotropic  movement 
such  as  plants  and  many  non-vertebrates  exhibit.  At  the  end  of 
some  hours  of  alternating  periods  of  active  locomotion  and  lethargic 
rest  most  of  the  individuals  are  found  collected  upon  one  side  of 
the  dish,  that  furthest  from  the  light. 

The  same  distribution  ultimately  results  when  the  dish  is  turned 
through  180°.  When  carried  to  the  door  of  the  laboratory  and 
exposed  to  the  direct  rays  of  the  sun  a  most  violent  commotion 
immediately  followed  and  soon  ^resulted  in  the  collection  of  all  the 
passive  individuals  upon  the  side  of  the  dish  most  remote  from  the 
source  of  light. 

Finally  when  the  dish  was  placed  in  the  centre  of  a  small  square 
room  lighted  by  a  window  on  the  north  and  one  on  the  east  and 
either  window  opened,  the  animals  collected  in  the  part  of  the  dish 
most  remote  from  that  window.  When  both  windows  remained 
open  the  position  of  the  lancelets  was  vaguely  that  part  of  the  dish 
most  remote  from  both  windows. 

As  far  as  these  experiments  go  they  may  be  taken  to  indicate 
that  we  have  a  case  of  negative  heliotropism  in  these  simple  verte- 
brates :  that  the  lancelets  move  away  from  the  source  of  light  along 
the  direction  of  its  rays  :  that  the  directive  action  of  the  sun's  rays 
is  as  in  the  numerous  non-vertebrates  studied  by  Dr.  J.  Loeb. 

Though  small,  the  largest  not  exceeding  a  length  of  16  mm., 
many  were  sexually  mature,  yet  individuals  kept  for  many  weeks 
did  not  discharge  ova,  except  in  one  collection  taken  early  in  June ;  in 
this  case  some  of  the  ova  were  naturally  fertilized  and  a  few  developed 
as  far  as  the  gastrula  stage,  when  they  were  destroyed  by  an  accident. 


AN  UNDESCRIBED  ACRANIATE.  215 

As  the  animal  is  small  and  translucent  the  course  of  food  and 
carmine  granules  may  be  traced  through  most  of  the  digestive 
tract.  The  strong  current  of  water  setting  into  the  pre-oral  cham- 
ber seems  to  be  controlled  by  the  longitudinal,  ciliated  ridges  of 
Miiller's  "Kaderorgan"  which  pass  forward  from  the  velum  on 
the  inside  of  each  lateral  wall  of  the  pre-oral  chamber.  Thus  the 
carmine  granules  pass  rapidly  along  these  ridges  towards  the  velum 
where  they  are  turned  inward  towards  the  aperture,  mouth,  at  the 
centre  of  the  velum.  The  granules  pass  along  in  strings  as  if  held 
together  by  a  thin  mucous ;  once  through  the  mouth  they  do  not 
pass  out  through  the  pharyngeal  slits  but  continue  along  the 
median  dorsal  pharyngeal  groove,  the  hyper-pharyngeal  groove, 
still  adhering  to  one  another  in  strings.  In  actual  longitudinal 
and  cross  sections  these  strings  of  granules  may  still  be  recognized 
in  the  ciliated  hyper-pharyngeal  groove. 


Explanation  of  diagram.  The  dotted  line  indicates  the  course  of  food  passing 
through  the  digestive  tract  which  is  divided  into  pre-oral  chamber,  pharynx, 
stomach  with  diverticulum  and  first  and  second  intestinal  regions. 

This  groove  leads  into  what  may  be  called  the  stomach  within 
which  the  current  of  granules,  or  the  granule  containing  mucous 
strand,  turns  abruptly  downwards  and  forwards  as  indicated  in 
the  above  diagram,  yet  does  not  enter  the  diverticulum  but,  still 
under  the  control  of  the  active  cilia  lining  the  digestive  tract,  passes 
back  again  through  the  centre  of  the  stomach.  It  is  now  revolving 
rapidly  in  a  constant  direction  from  right  to  left  and  continues  to 
do  so  throughout  the  next  division  of  the  digestive  tract,  the  first 
or  larger  section  of  the  intestine.  In  this  part  of  the  intestine  the 
granules,  diatomes,  etc.,  collect  into  clumps  separated  by  the  clear 
part  of  the  continuous  mucous-like  strand.  In  this  region  the 
intestinal  epithelium  is  especially  modified  in  a  zone  that  became 
very  prominent  when  staining  reagents  are  used. 

The  second,  final  and  smaller  part  of  the  intestine,  contains  pellets 
of  detritus  that  become  successively  larger  towards  the  anus  where 


216  E.  A.  ANDREWS. 

they  have  the  form  of  elongated,  not  spherical  masses  that  are  dis- 
charged from  the  anus  as  the  anal  sphincter  relaxes  from  time  to  time. 
The  mucous  strand  is  here  broken,  the  granular  aggregates  becoming 
isolated  from  one  another.  These  balls  or  pellets  move  along  but 
slowly  and  give  up  the  revolving  motion  seen  in  the  first  part  of 
the  intestine  and  in  the  stomach. 

The  time  elapsing  from  the  addition  of  carmine  to  the  water  to 
the  discharge  of  carmine  containing  pellets  may  be  much  less  than 
one  hour. 

Though  no  carmine  was  seen  to  enter  the  diverticnlum,  yet  after 
twenty-four  hours  its  walls  became  pink  from  the  accumulation  of 
fine  granules  that,  in  sections,  are  seen  to  lie  within  the  epithelial 
cells  of  this  part  of  the  digestive  tract.  When  the  animal  is  kept 
long  in  sand  and  water  to  which  carmine  is  added  from  time  to 
time,  this  is  taken  up  by  many  cells  on  the  branchial  arches  as  well 
as  by  the  cells  of  the  stomach  and  intestine.  Moreover,  as  demon- 
strated by  Weiss  (24)  for  the  European  Amphioxus,  many  cells  of 
the  atrium  take  up  the  carmine,  notably  those  forming  the  so-called 
nephridial  ridges  and  those  in  the  pigmented,  dorsal  atrial  pouches. 
The  nephridia,  however,  could  not  be  recognized  in  sections  of  such 
individuals. 

After  some  weeks  the  pre-oral  organ  was  found  darkly  stained 
by  the  carmine,  but  not  uniformly  so  :  the  closed  deep  lying  part 
contained  most  of  the  red  in  the  form  of  radiating  spherules  as  if 
in  gland  cells  while  the  tubular  part  of  the  organ  opening  into 
the  pre-oral  chamber  had  a  decidedly  yellow  color  with  only  diffused 
red  in  the  free  ends  of  the  cells  and  very  few  red  granules  in  their 
basal  parts.  This  appearance  of  the  pre-oral  organ  suggested  at 
the  time  that  it  might  have  a  nephridial  function. 

When  Bismarck  brown  is  added  to  the  water  in  which  the  live 
animals  are  kept,  they  soon  became  darkly  stained.  On  sectioning, 
this  stain  is  found  to  be  due  to  fine  spherules  in  the  cells  of  the 
epidermis,  digestive  tract,  atrium  and  testis  and  also  in  the  cells 
lining  lymph  spaces.  Here  again  the  method  failed  in  revealing 
nephridia. 

The  vitality  of  injured  specimens  is  very  great;  even  those  cut 
into  two  live  for  some  days.  In  such  cases  some  regeneration  of 
lost  parts  may  be  initiated.  Thus  when  the  tail  was  cut  off  just 


AN  UNDESGRIBED  A  CRANIATE.  21T 

posterior  to  or  at  the  anus,  a  blunt  process  grew  out  from  the 
healed-over  wound.  On  examination  by  sectioning,  this  process  was 
found  to  contain  notochord,  anus  and  nerve  tube  and  to  be  covered 
by  a  complete  new  epidermis.  Here,  as  in  the  tadpole  or  sala- 
mander, there  seems  to  be  a  regeneration  of  each  tissue  to  form 
new  tissue  of  its  own  kind.  The  epidermis  was  continuous  with 
the  old  one  and  underlaid  by  a  delicate  connective  tissue  lamella 
continuous  with  the  much  thicker  one  under  the  old  epidermis. 
The  nerve  tube  was  a  collection  of  a  few  large  cells  continuous 
with  the  walls  of  the  old  nerve  cord  and  surrounding  a  relatively 
large  central  lumen.  The  notochord  had  grown  out  very  much  as 
in  the  figures  of  Siredon  given  by  Barfurth  and  was  enclosed  in  a 
delicate  sheath  continuous  with  the  stout  sheath  of  the  old  cord. 
The  digestive  tract  was  continued  to  the  surface  of  the  body  where 
its  lining  cells  became  continuous  with  the  outer  epidermis.  The 
muscles  of  the  last  pair  of  myotomes  appeared  to  be  broken  down 
into  an  amorphous  mass  that  was  continuous  with  a  new  meso- 
dermal  formation  in  the  new  tail.  This  mesoderm  mass  consisted 
of  a  loose  sponge-work  of  cells  arranged  in  the  proximal  part 
of  the  new  growth  so  as  to  surround  segmentally-placed  cavities. 
Large  blood,  or  coelomic,  spaces  full  of  coagulum  or  lymph  also 
occurred  in  this  part  of  the  new  outgrowth. 

With  sufficient  care  the  specimens  might  well  have  regenerated 
complete  post  anal  regions — as  far  as  could  be  surmised  from  these 
few  observations. 

Coming  now  to  the  chief  anatomical  peculiarities  of  this  new 
Acraniate  we  find  them  expressed  in  the  asymmetry  of  the  repro- 
ductive organs  and  in  the  character  of  the  fins. 

In  the  living  animal  the  reproductive  organs,  ovaries  and  testes, 
may  be  easily  seen  through  the  body-wall,  but  much  more  readily 
from  the  right  side  (Fig.  1)  than  from  the  left  (Fig.  2).  This  is  due 
to  the  fact  that  the  gonads  form  a  single  series  present  only  upon  the 
right  side  of  the  animal  and  are  not  paired  as  in  all  other  Acraniata 
and  in  most  all  Craniata.  From  the  right  this  single  series  of 
gonads  shows  plainly  through  the  wall  of  the  atrium  while  from 
the  left  it  is  more  or  less  concealed  by  both  sides  of  the  pharynx, 
the  left  wall  of  the  atrium  and,  in  part,  by  the  caecal  pouch  that 
lies  on  the  left  of  the  animal. 


218  E.  A.  ANDREWS. 

This  is  obvious  in  transverse  sections  (Fig.  14)  where  the  gonad, 
In  this  case  an  ovary,  though  having  the  normal  relation  and 
position  of  those  found  in  a  common  Amphioxus  and  so  developed 
-as  to  crowd  the  digestive  organs  out  of  place,  is  yet  found  only  upon 
the  right  side.  Longitudinal  sections  show  the  entire  series  of 
gonads  all  upon  the  right  side  so  that  there  is  no  question  of 
alternate  crowding  of  left  and  right  gonads  into  a  single  series. 
Both  testes  and  ovaries  alike  exhibit  this  asymmetrical  develop- 
ment, though  otherwise  like  those  of  other  lancelets. 

That  this  single  right  series  corresponds  to  the  right  series  of 
Amphioxus  without  admixture  of  the  left  is  indicated  by  its  presence 
as  a  single  right  series  in  the  youngest  individuals  observed.  Thus 
in  a  specimen  6  mm.  long  (Fig.  5)  the  gonads  are  a  single,  right 
series  of  minute  collections  of  few  large  cells,  the  sex  as  yet  un- 
recognizable, having  the  same  position  and  character  as  the  early 
stages  of  the  gonads  on  right  or  left  of  the  common  Amphioxus  as 
figured  by  Boveri  (25  Fig.  8). 

It  is  thus  evident  that  the  asymmetry  of  the  reproductive  organs 
goes  back  to  an  early  stage  and  is  probably  due  to  the  lack  of  de- 
velopment of  the  left  series  found  in  other  Acraniata.  Whether 
there  is  at  the  first  any  start  of  this  missing  left  series  cannot  be 
determined  at  present. 

The  gonads  differ  from  those  of  the  known  lancelets  in  being 
somewhat  more  numerous  on  the  right  side.  Thus  while  the 
European  form  has  according  to  Lankester  (23)  but  26  gonads  on 
the  right  (and  as  many  on  the  left)  this  Bahama  form  has  29  as 
seen  in  Fig.'l.  They  begin  at  the  fifteenth  myotome,  gradually 
increase  greatly  in  size,  become  consequently  crowded  together 
(since  each  corresponds  to  a  myotome),  rather  suddenly  decrease 
in  size  posterior  to  the  branchial  region  and  end  anterior  to  the 
atriopore  by  a  very  small  gonad  like  the  first  of  the  series,  lying 
in  the  forty-third  metamere.1 

No  observations  were  made  upon  the  method  of  discharge  of 
sexual  products,  but  in  sections  ova  and  sperm  are  found  in  all  parts 
of  the  digestive  tract,  in  the  pre-oral  chamber,  stomach,  intestine 
and  extreme  end  of  the  rectum.  In  some  cases  the  ova  in  the 

*In  Fig.  1  the  correspondence  between  myotomes  and  ovaries  has  not  been 
correctly  represented. 


AN  UNDESCEIBED  ACEANIATE.  219 

intestine  show  the  first  cleaveage  spindles,  having  been  fertilized. 
As  all  these  cases  were  specimens  kept  in  confinement  we  infer  that 
these  sexual  products  were  probably  swallowed  and  give  no  evidence 
as  to  the  method  of  discharge  from  the  gonads.  None  were  found 
free  in  the  atrium ;  and  in  some  cases  the  individual  with  ova  in 
its  digestive  tract  was  sexually  immature. 

Even  more  conspicuous  than  this  asymmetry  of  the  reproductive 
organs  is  the  character  of  the  fins  at  the  posterior  end  of  the  animal. 

As  seen  in  Figs.  1,  2,  4,  there  is  a  long  slender  caudal  process 
extending  posterior  to  the  last  myotome.  This  process  is  composed 
of  the  rather  low  dorsal  and  ventral  median  fins  which  become 
continuous  at  its  tip  but  are  elsewhere  separated  by  the  supporting 
notochord  that  extends  nearly  to  the  very  tip  of  the  caudal  pro- 
cess. Moreover  the  nerve  cord  runs  back  in  this  caudal  process 
as  a  slender  tube  just  dorsal  to  the  notochord  and  finally  diminish- 
ing to  a  few  cells  surrounding  a  lumen  at  the  extreme  tip  of  the 
process.  In  a  transverse  section  (Fig.  23)  taken  about  the  region 
h  of  Fig.  4  the  dorsal  and  ventral  fins  are  almost  identical  in  size 
and  structure.  Each  is  a  clear  matrix  of  connective  tissue  perme- 
ated by  irregularly  radiating,  anastomosing  canals  lined  by  cells 
that  may  nearly  fill  them,  as  represented  to  the  extreme  right  in 
Fig.  25.  This  clear  substance  is  concentrated  as  a  sheath  about 
the  notochord  and  serves  peripherally  as  a  support  for  the  single 
layer  of  epidermal  cells  covering  the  caudal  process  as  all  other 
parts  of  the  body.  The  minute  nerve  cord  has  ganglion  cells  but 
no  pigment.  The  numerous  nerves  branching  through  the  caudal 
process  come  for  the  most  part,  if  not  altogether,  from  the  neural 
tube  anterior  to  the  caudal  process. 

In  the  youngest  forms  found,  having  a  length  of  6  mm.  and 
22  branchial  clefts  on  a  side,  the  caudal  process  is  very  much 
shorter,  not  narrowed,  but  on  the  contrary  expanded  as  the  charac- 
teristic, rounded,  larval  tail-fin  (Fig.  5).  Soon,  however,  this 
rounded  tail-fin  becomes  pointed,  as  seen  in  a  specimen  with  twenty- 
seven  branchial  slits  (Fig.  3),  and  subsequently  elongated  as  in  the 
sexually  mature  individuals. 

Where  the  caudal  process  springs  from  the  myotome  region  the 
ventral  and  the  dorsal  median  fins  both  suddenly  increase  in  height, 
the  ventral  much  more  than  the  dorsal. 


220  E.  A.  ANDREWS. 

If  we  now  trace  the  dorsal  fin  anteriorly  in  the  region  of  the 
posterior  myotomes  we  find  that  the  lymph  canals  that  penetrate 
its  substance  become  arranged  in  definite,  parallel  lines  radiating 
upward  from  near  the  neural  cord.  Several  of  these  canals  occur 
opposite  each  myotome  and  some  connect  with  large  lymph  spaces 
now  appearing  just  above  the  neural  cord.  As  seen  in  Fig.  25,  a 
surface  view  from  an  animal  living  in  sand  with  Bismarck  brown, 
granules  of  brown  substance  occur  in  large  cells  lining  the  canals 
and  the  lymph  cavities.  These  cavities  become  larger  and  more 
regular  anteriorly  and  form  the  fin-ray  spaces  of  the  dorsal  fin, 
three  or  four  for  each  myotome.  Henceforth  the  dorsal  fin  becomes 
more  and  more  predominantly  made  up  of  these  lymph  spaces  which 
succeed  one  another  in  a  constant  crowded  series  as  seen  in  Figs.  1, 
2,  3,  4  and  in  Fig.  17. 

The  lymph  canals  still  remain  and  at  places  open  into  the  fin- 
ray  spaces,  from  the  summits  of  which  they  extend  out  into  the  fin. 
Though  at  first  nearly  vertical  (Fig.  25)  these  canals  bend  backwards 
more  and  more  until,  anteriorly,  they  come  to  run  nearly  parallel 
to  the  dorsal  edge  of  the  fin  and  will  appear  in  transverse  sections 
as  in  Fig.  22. 

The  fin-ray  spaces  are  lined  by  a  membrane  with  distinct  cells 
projecting  into  the  lumen  (Fig.  17).  Though  at  first  quite  near  the 
nerve  cord  the  spaces  gradually  rise,  anteriorly,  as  the  muscles 
become  vertically  deeper,  and  thus  come  to  be  separated  from  the 
nerve  cord  by  a  considerable  space  as  seen  in  Figs.  22,  14,  12. 

Projecting  into  each  well  formed  fin-ray  space,  but  not  into  the 
imperfect  posterior  ones  represented  in  Fig.  25,  there  is  a  ventral 
mass  of  solid  connective  tissue,  the  so-called  fin-ray.  These  fin- 
rays  (Fig.  17)  vary  much  in  size  and  shape  in  differently  prepared 
specimens  but  never  appear  as  prominent  as  in  some  species  of 
Amphioxus.  They  are  not  paired  but  single,  median  upgrowths 
from  the  ventral  wall  of  each  fin-ray  space. 

About  the  middle  of  the  branchial  region  the  proportions  of  the 
fin-rays  and  fin-ray  spaces  are  as  in  Fig.  17,  but  posteriorly  they 
became  more  crowded  and  deeper  vertically,  most  so  over  the  region 
of  the  atriopore  and  just  posterior  to  that  region.  Anteriorly  the 
spaces  become  more  shallow  and  longer  till  finally  the  fin-rays 
cease  to  exist  over  the  pre-oral  chamber  while  the  fin-ray  spaces 


AN  UNDESCRIBED  ACRANIATE.  221 

continue  as  flattened  cavities.  Anterior  to  the  pre-oral  chamber 
only  a  few  very  small  irregular  median  spaces  remain  as  repre- 
sentatives of  the  fin-ray  spaces.  As  seen  in  Fig.  10,  the  most  an- 
terior of  these  opens  into  a  large  unsegmented,  median  space  that 
comes  down  abruptly  into  proximity  with  the  brain,  where  it  ends 
dorsal  to  the  pigment  spot  that  limits  the  anterior  end  of  the  brain. 

As  is  evident  from  the  figure  this  space  opens  into  at  least  one 
of  a  series  of  long  lymph  canals  passing  back  dorsal  to  the  fin-ray 
spaces  in  the  substance  of  the  dorsal  fin.  Such  canals  are  seen  cut 
in  cross  section  in  Figs.  1,  3, 15,  21,  22,  23.  Many  of  these  canals 
arise  still  further  forward  from  vertical,  radiating  canals  anterior 
to  the  brain,  canals  that  differ  from  those  in  the  posterior  part  of 
the  body  (Fig.  25)  chiefly  in  having  no  swollen  base,  or  incipient 
fin-ray  space.  In  the  anterior  region  there  is,  however,  what  may 
be  regarded  as  a  representative  of  an  undifferentiated  series  of  fin- 
ray  spaces  developed  as  a  single  unsegmented  space  lying  immedi- 
ately above  the  notochord  and  extending  forward  from  the  brain 
almost  to  the  extreme  tip  of  the  notochord.  This  terminal  space 
has  no  connection  with  the  one  dorsal  to  the  brain  and  is  hence  cut 
off  from  the  series  of  fin-ray  spaces  by  an  interval  above  the  pig- 
ment spot. 

In  this  interval  lies  a  minute  intermediate  lymph  space,  as  shown 
in  Fig.  10. 

Anteriorly  the  terminal  space  appears  constricted  into  partially 
separate,  minute  spaces  near  the  tip  of  the  notochord.  A  transverse 
section  taken  near  the  tip  of  the  notochord  (Fig.  11)  shows  this 
terminal  space  and  a  few  of  the  lymph  canals  imbedded  in  the  smalf 
amount  of  connective  tissue  that  makes  up  the  dorsal  fin. 

Throughout  the  dorsal  fin  the  lymph  canals  have  a  nearly  verti- 
cal position  at  the  anterior  and  posterior  ends  but  elsewhere  become 
more  nearly  horizontal.  Those  from  the  anterior  region  running 
backward  (Fig.  10)  incline  more  and  more  and  diminish  in  num- 
ber (Fig.  17),  while  those  from  the  posterior  end  turning  forward 
supply  all  the  posterior  part  of  the  fin. 

If  now  the  ventral  median  fin  be  traced  forward  from  the  caudal 
process  it  will  be  found  to  present  the  same  structure  as  the  dorsal 
fin  with  the  important  exception  that  it  contains  no  fin-rays  nor 
fin-ray  spaces  :  thus  it  differs  from  the  ventral  fin  of  other  lancelets. 


222  E.  A.  ANDREWS. 

The  radiating  vertical  canals  are  very  long  in  the  deep  fin  beneath 
the  posterior  myotomes  and  present  slight  proximal  swellings  in 
the  region  just  posterior  to  the  anus ;  swellings  that  are  like  those 
more  posterior  ones  of  the  dorsal  fin  represented  in  Fig.  25. 

Anterior  to  the  anus,  however,  these  spaces  are  not  continued  as 
fin-ray  spaces  similar  to  those  of  the  dorsal  fin ;  in  fact  there  are  no 
representatives  of  such  spaces  and  the  lymph  canals  cease  to  form 
parallel,  vertical  channels  and  anastomose  in  an  irregular  way. 

There  are  thus  no  double  fin-rays  in  the  region  between  the 
anus  and  atriopore  though  such  are  believed  to  exist  in  all  other 
Acraniata :  a  striking  and  important  difference. 

At  the  extreme  anterior  tip  of  the  animal  the  ventral  fin  has 
the  same  structure  as  the  dorsal,  with  which  it  is  continuous  around 
the  anterior  end  of  the  notochord  (Fig.  10). 

In  this  region  the  ventral  fin  has  also  a  large  median  lymph 
space  that  anteriorly  is  somewhat  sub-divided  near  the  tip  of  the 
notochord,  but  posteriorly  expands  vertically  as  a  large  median 
space  that  penetrates  some  distance  into  the  ventral  fin  and  then 
rises  again  to  end  abruptly  anterior  to  the  pre-oral  chamber  oppo- 
site the  posterior  end  of  the  second  myotome  (Fig.  10).  In  trans- 
verse section,  near  the  tip  of  the  notochord,  this  ventral  space 
(Fig.  11)  is  smaller  than  the  dorsal  space,  but  in  sections  posterior 
to  the  brain  it  is  in  every  way  larger  than  the  dorsal  spaces  above 
the  nerve  cord. 

Between  this  anterior  end  of  the  median  fin  and  the  posterior 
part  in  the  caudal  process  important  modifications  of  the  median 
fin,  in  fact  its  entire  disappearance  as  a  median  fin,  are  brought 
about  in  connection  with  the  openings  of  the  digestive  and 
branchial  cavities.  These  modifications  are  the  departure  of  the 
median  fin  from  a  true  median  position,  and  the  substitution  of  the 
paired  rnetapleural  folds  in  place  of  a  median  fin  throughout  the 
length  of  the  branchial  region. 

The  appearances  seen  in  the  youngest  specimens  favor  that  ex- 
planation of  the  formation  of  the  atrium  given  by  Willey  (26)  so 
that  we  may  adopt  the  terms  sub-atrial  ridges  for  the  horizontal 
outgrowths  of  the  metapleural  folds  and  abandon  the  older  idea  of 
extensive  epipleural  downgrowths.  The  complete  metapleura  have 
the  same  structure  and  relationship  as  in  the  common  amphioxus, 


AN  UNDESCRIBED  A  CRANIATE.  223 

starting  from  the  pre-oral  hood  they  run  back  parallel  with  one 
another  as  far  as  the  atriopore,  thus  forming  the  lateral  limits  of 
the  floor  of  the  atrium.  They  do  not  stop  at  the  atriopore,  but  as 
seen  in  Figs.  1,  2,  3,  4,  5,  continue  posteriority,  the  left  one  but  a 
short  distance,  the  right  one,  however,  becoming  continuous  with 
the  median  ventral  fin.  This  continuity  of  the  median  ventral  fin 
and  the  right  metapleuron  can  be  seen  in  surface  views  (Figs.  1—5), 
and  also  demonstrated  in  serial  sections. 

Such  sections  show  that  the  fin  retains  its  solid  structure  up  to 
point  anterior  to  the  atriopore  where  it,  or  the  metapleuron  as 
we  may  now  call  it,  acquired  the  usual  hollow  condition  known 
in  other  lancelets.  The  left  metapleuron  likewise  is  solid  and 
identical  with  a  fin  in  structure  at  its  posterior  end.  In  a  section 
across  the  middle  of  the  body  (Fig.  14)  we  see  two  hollow  metapleura, 
but  at  the  level  of  the  atriopore  (Fig.  1 5)  there  are  two  fins,  the  left 
the  smaller.  Following  a  few  sections  forward  from  the  atriopore 
the  thick  connective  mass  of  the  fins  is  found  to  continue  as  the 
thick  sub-epidermal  layer  on  the  outer  side  of  the  metapleura, 
while  a  new  cavity,  the  large  lymph  space  of  the  metapleura, 
gradually  extends  downward  from  the  basal  part  of  each  fin,  or 
metapleuron. 

This  continuity  of  the  right  metapleuron  with  the  median  fin  is 
unlike  the  condition  found  in  the  European  Amphioxus  and  leads  to 
an  interesting  departure  of  the  fin  from  its  true  median  position.  In 
passing  forward  from  the  tail  process  the  median  fin  departs  de- 
cidedly to  the  right,  even  before  the  anus  is  reached,  and  becomes 
attached  along  the  right  edge  of  the  ventral  aspect. 

Where  the  anus  opens  out  on  an  anal  papilla  (Fig.  22)  the  fin 
is  on  the  right  side.  We  see  here  that  though  the  digestive  tract 
discharges  to  the  left  of  the  median  fin  it  is  not  at  all  asymmetrical 
with  reference  to  the  median  plane  of  the  animal :  it  is  the  fin 
which  is  placed  on  the  right,  while  the  digestive  tract  remains  a 
median  structure.  Yet  the  actual  orifice  of  the  rectum  may,  as  in 
the  figure,  be  turned  to  one  side  and  lie  to  the  left  of  the  median 
plane;  the  papilla  with  its  sphincter  muscles  is  not  accurately 
bisected  by  the  median  plane,  but  this  does  not  justify  us  in  regard- 
ing the  anus  as  morphologically  out  of  the  median  plane. 


224  E.  A.  ANDREWS. 

Immediately  anterior  to  the  anus  the  rectum  is  median  (Fig.  21) 
and  the  fin  is  on  the  right  side ;  but  before  the  atriopore  is  reached 
it  approaches  the  median  line  and  appears  as  a  true  median  structure 
as  far  as  its  free  portion  is  concerned.  The  basal  part,  however, 
even  when  the  free  edge  is  median,  extends  up  to  an  attachment 
to  the  muscular  region  of  the  right,  much  as  is  seen  in  Figure  21. 
Even  its  free  part  is  median  only  for  a  short  space  and  soon  pro- 
jects again  from  the  right  side,  becoming  thus  continuous  with  the 
right  metapleuron  posterior  to  the  atriopore,  as  is  shown  in  Fig. 
15,  where  the  left  metapleuron  is  seen  in  a  similar  fin-like  state 
and  the  posterior  tip  of  the  atrioporal  spout  is  enclosed  between 
the  two. 

The  departure  of  the  median  fin  from  a  true  median  position  is 
correlated  with  the  breaking  through  of  the  median  rectum  :  anterior 
to  the  anus  the  fin  becomes  more  nearly  median  in  proportion  as 
the  rectum  rises  up  from  its  superficial  ventral  position  or  is  more 
and  more  enclosed  by  the  downward  extension  of  the  lateral  muscles, 
passing  from  the  opening  seen  in  Fig.  22  through  a  stage  shown 
in  Fig.  21  to  a  position  shown  in  Fig.  15.  Here,  however,  the 
atrial  formations  again  interfere  with  the  median  position  of  the 
fin,  and  it  becomes  lost  in  the  right  metapleuron. 

The  continuity  of  right  metapleuron  and  fin  suggests  that  the 
fin  may  not  be  primarily  a  median  structure,  but  one  of  a  pair  of 
longitudinal  folds  of  which  the  left  forms  only  the  left  metapleuron 
while  the  right  is  more  extensive  and  comes  to  lie  in  the  median 
plane,  as  a  locomotor  organ,  whenever  the  atrium  and  digestive  tract 
are  not  at  the  surface  to  render  such  a  position  difficult. 

The  idea  that  the  median  fin  is  but  a  form  of  the  right  meta- 
pleuron would  not  harmonize  with  the  view  suggested  by  Lan- 
kester  (23),  that  the  double  ventral  fin  of  amphioxus  may  be  the 
fused  epipleura,  but  that  view  would  require  re-stating  if  we  accept 
the  formation  of  the  atrium  as  recently  described  (26). 

As  we  have  seen  the  median  ventral  fin  of  the  caudal  process 
continue  around  the  end  of  the  notochord,  thence  along  the  whole 
dorsal  median  line  and  finally  become  continuous  with  a  median 
ventral  fin  beneath  the  anterior  end  of  the  notochord,  nowhere 
showing  any  trace  of  a  double  or  paired  character,  we  might  expect 
that  it  would  become  continuous  with  the  right  metapleuron 


AN  UNDESCRIBED  A  CRANIATE.  225 

anteriorly  as  well  as  posteriorly.  According  to  Lankester  (23)  this 
is  the  case  in  amphioxus  if  we  regard  the  right  half  of  the  pre-oral 
hood  as  a  continuation  of  the  right  "  epipleuron."  But  in  the 
Bahama  amphioxus  both  metapleura  seem  to  be  continuous  with 
the  side  of  the  hood,  these  with  the  edges  of  the  anterior  part  of  the 
pre-oral  chamber  and  these  in  turn  with  the  single  median  fin  (Fig.  6). 

In  Fig.  13,  which  is  a  section  across  the  base  of  the  hood,  the 
connective  tissue  mass  joining  the  shrunken-in  hood  membrane  to 
the  lateral  muscle  mass  of  each  side  is  a  direct  continuation  of 
and  is  some  sort  a  representative  of  the  metapleuron  of  each  side. 
Again  in  the  section  Fig.  1 2,  anterior  to  the  free  edge  of  the  hood 
the  same  connective-tissue  masses  now  project  freely  and  form  edges 
to  the  pre-oral  chamber.  They  are  much  like  the  fins,  or  meta- 
plura,  posterior  to  the  atriopore  (Fig.  15). 

Even  if  we  may  thus  regard  the  metapleura  as  continuous  with 
the  sides  of  the  pre-oral  hood  and  the  anterior  edges  of  the  pre-oral 
chamber,  we  are  puzzled  by  the  fact  that  they  meet  at  the  anterior 
end  of  the  pre-oral  chamber  and  became  continuous  with  the 
median  fin  (Figs.  6,  20).  At  the  same  time  the  right  predomi- 
nates here  also  and  it  is  chiefly  the  right  side  of  the  pre-oral 
chamber  which  is  fringed  by  a  continuation  of  the  median  fin.  As 
the  median  fin  is  thus  posteriorly  continuous  with  a  single  paired 
structure,  the  right  metapleuron,  and  anteriorly  continues  with  what 
appears  to  be  two  paired  structures,  both  metapleura,  we  see  no  sure 
ground  for  inferring  its  origin,  either  from  the  loss  of  one,  or  from 
the  fusion  of  both  of  a  primitive  pair  of  organs.  Yet  the  indications 
are  that  the  median  fin  is  not  so  much  single  by  fusion  as  by  loss 
of  its  fellow. 

As  illustrating  the  ease  with  which  paired  lateral  structures  may 
pass  to  a  median  ventral  position  and  vice  versa,  this  case  is  of 
interest  with  reference  to  the  origin  of  appendages  of  fishes  from 
lateral  fins  and  their  connection  with  a  median  fin. 

The  disappearing  metapleura  on  the  sides  of  the  pre-oral  chamber 
are  intimately  associated  with  the  pre-oral  hood.  This  structure 
is  much  more  extensive  than  in  the  common  Amphioxus,  forming  a 
deep  shovel-shaped  or  inflated  membrane  suspended  from  the  pos- 
terior and  lateral  margins  of  the  pre-oral  depression;  when  ex- 
panded it  appears  as  in  Fig.  6. 


226  E.  A.  ANDREWS. 

From  a  side  view  (Fig.  1,  2,  3,  4)  it  extends  forward  ventrally 
over  the  pre-oral  chamber  like  a  hood,  with  cirri  like  those  of  other 
lancelets.  These  cirri,  however,  are  perfectly  smooth  as  shown  in 
Fig.  19  and  do  not  present  the  denticulate  outlines  due  to  the 
special  sense  •  organs  found  on  the  cirri  of  other  Acraniata.  The 
number  of  cirri  is  15  to  21,  the  small  lateral,  anterior  ones  being 
involuted  dorsally  with  the  membrane  and  not  seen  from  a  ventral 
view  (Fig.  6).  There  may  be  a  median  cirrus  and  an  equal  number 
of  paired  cirri  on  each  side,  as  seen  in  the  view  of  the  macerated 
skeleton  (Fig.  24).  Each  cirrus  is  supported  by  a  special  carti- 
lage-like rod  springing  from  a  common  curved  and  jointed  basal 
arch,  as  in  the  common  lancelet.  Each  rod,  it  will  be  observed, 
springs  from  the  distal  end  of  one  of  the  basal  pieces  composing 
the  common  basis  for  all  the  rods.  The  hood  differs  from  that  of 
the  European  form,  and  from  that  of  the  Florida  form  also,  in 
having  the  membrane  continued  up  over  nearly  the  whole  length 
of  the  cirri,  leaving  but  their  tips  free.  Moreover  the  median  cirrus 
is  so  long,  and  the  most  lateral  so  short  that  there  is  no  reason  to 
doubt  that  the  latter  are  the  youngest  as  has  been  shown  to  be  the 
case  in  Amphioxus  (27)  although  before  the  embryological  facts  were 
known  the  examination  of  the  adults  had  led  Lankester  (23)  to  the 
opposite  conclusion. 

If  we  were  justified  in  regarding  the  lateral  edges  of  the  pre-oral 
chamber  as  continuations  of  the  metapleura,  it  is  tempting  to  sup- 
pose that  the  hood  membrane,  lying  between  those  continued 
metapleura  and  posteriorly  continuous  with  the  floor  of  the  atrium 
(Fig.  6)  may  be  homologous  with  the  sub-atrial  ridges,  may  have 
been  originally  an  anterior  continuation  of  those  parts  of  the  meta- 
pleura which  now  unite  posteriorly  to  form  the  floor  of  the  atrium. 
Such  a  view  may  be  supported  by  the  fact  that  in  amphioxus,  as 
Willey  has  discovered  (27),  the  oral  hood  arises  from  two  beginnings 
one  right  and  one  left :  while  other  facts  that  militate  against  it  may 
be  explained  as  secondary  acquisitions  connected  with  the  remarka- 
ble asymmetry  of  the  oral  region  of  the  Acraniata. 

In  addition  to  the  above  peculiar  features  of  the  reproductive 
organs  and  fins,  the  Bahama  lancelet  presents  some  few  minor  ana- 
tomical features  which  may  now  be  described  in  comparison  with 
the  similar  structures  in  the  European  forms. 


AN  UNDESCRIBED  ACRANIATE.  227 

The  true  mouth  is  at  the  centre  of  a  transverse  velum  provided 
with  a  strong  sphincter  muscle  and  a  series  of  oral  tentacles  that 
are  not,  apparently,  quite  as  numerous  as  in  the  European  lancelet 
though  having  the  same  arrangement. 

The  capacious  pre-oral  chamber  bears  upon  its  side  wall  the 
so-called  "  Raderorgan,"  consisting  of  three  large  ridges  of  specially 
thickened,  ciliated  epithelium,  passing  forward  on  each  lateral  wall 
(Figs.  1,  2)  to  end  in  rounded  lobes  in  the  posterior  half  of  the 
chamber  above  the  basal  part  of  the  pre-oral  hood.  These  ridges 
might  be  regarded  as  one  continuous  ridge  folded  back  and  forth 
into  three  chief  loops  with  smaller  lobes  interpolated  between  them 
at  the  posterior  end.  All  the  ridges  continue  posteriorly  as  a  cili- 
ated area  leading  to  the  velum  and  out  on  it  towards  its  central 
aperture,  the  mouth.  An  important  part  of  the  structure  is  a  special 
ridge  found  only  upon  the  right  side,  high  up  towards  the  noto- 
chord,  so  that  it  appears  median  from  a  side  view  (Fig.  1).  In 
sections "  anterior  to  the  above  paired  ridges  (Fig.  13)  this  right, 
azygos  ridge  continues  to  end  only  at  the  extreme  anterior  angle  of 
the  pre-oral  chamber.  Here  it  is  associated  with  the  conspicuous 
pre-oral  pit  found  on  the  right  side  in  the  position  shown  in  Fig. 
1 2,  but  continues  as  a  special  ciliated  ridge  even  anterior  to  the 
pit  (Fig.  18)  as  well  as  posteriorly  to  join  the  other  ridges  at  the 
velum. 

The  pit  has  the  form  of  a  glandular  tube,  somewhat  bent,  opening 
out  into  the  pre-oral  chamber  in  the  azygos  ridge  and  histologically 
divided  into  two  regions.  The  terminal  part  is  ciliated,  the  internal 
closed  end  has  an  epithelium  of  what  appear  to  be  gland  cells 
casting  out  a  coagulable  substance  into  the  lumen.  As  already 
stated  the  two  regions  of  the  organ  behave  differently  when  the 
animal  is  fed  with  carmine. 

That  the  pit  has  either  an  excretory  function  or,  more  probably, 
may  serve  to  secrete  slime  to  aid  in  entangling  food  particles  to 
be  swept  back  to  the  mouth,  is  an  idea  suggested  by  its  action 
towards  carmine  and  strengthened  by  its  anatomical  relations  to  a 
large  blood  vessel  or  space.  This  vessel  passes  along  close  beneath 
the  azygos  ridge  for  its  whole  length  (Figs.  12,  13)  and  is  the 
"  aortic  arch  "  of  Langerhans  (28)  as  figured  by  Ralph  (29)  and 
described  by  Lankester  (23)  and  recently  called  a  "  glomus  "  by  van 


228  E.  A.  ANDREWS. 

Wijhe  (32),  who  regards  it  as  of  excretory  function.  It  seems  to  be 
much  less  complex  than  in  the  European  form  ;  though  it  presents 
some  branches  anteriorly  it  is  not  to  be  regarded  as  a  glomus 
here.  Posteriorly  it  passes  between  the  velum  and  the  lateral 
muscles  but  could  not  be  traced  into  connection  with  other  vessels. 
Anteriorly  it  passes  between  the  walls  of  the  pit  and  the  azygos 
ridge,  close  to  each  end  bends  up  dorsally  between  the  tip  of  the  pit 
and  the  end  of  the  ridge.  Here  it  immediately  unites,  at  the  an- 
terior end  of  the  pre-oral  chamber,  with  a  large  branch  of  the  left 
aorta,  forming  thus  a  median  aortic  trunk  that  runs  forward  a 
short  distance,  close  beneath  the  notochord,  bifurcates,  and  ends  in 
the  ventral  sheath  of  the  notochord.  This  left  aorta  is  notably 
smaller  than  the  "right  arch"  (Figs.  12,  13)  and  branches  just 
before  the  anterior  end  of  the  pre-oral  chamber  is  reached,  sending 
the  larger  branch  to  fuse  with  the  "  right  arch,"  as  above  stated, 
and  the  smaller  branch  forward  a  short  distance  to  branch  in  turn 
and,  perhaps,  to  connect  with  the  large  median  lymph  space  begin- 
ning here  and  lying  under  the  notochord  as  seen  in  Fig.  10. 

Of  the  two  aortic  trunks  found  in  the  pharyngeal  region  it  is 
only  the  left  that  connects,  as  above,  with  the  "  right  arch."  The 
right  aorta  seems  to  disappear  in  the  velum. 

No  attempt  has  been  made  to  trace  out  the  rest  of  the  vascular 
system  though  the  chief  aortic  trunk,  the  vessels  of  the  branchiae, 
and  the  numerous  vessels  on  the  posterior  intestine  and  caecum  seem, 
in  sections,  to  be  much  as  described  for  the  common  Amphioxus. 

The  branchial  apparatus  is  like  that  of  the  known  forms ;  but 
as  seen  in  Figure  2  the  first  gill-slit  may  be  small  and  only  partly 
divided  by  a  tongue  bar,  while  in  the  European  species  van 
Wijhe  (32)  finds  that  the  first  gill  slit  has  no  tongue  bar.  In 
macerations  of  the  branchial  skeleton  we  find  the  usual  primary 
bars  and  tongue  bars  represented  by  rods  that  are  double  in  the 
former,  divaricating  at  the  lower  end  and  deeply  cleft  lengthwise, 
but  apparently  single  in  the  latter,  though  marked  longitudinally 
by  cavities  and  grooves. 

Primary  rods  and  tongue  bar  rods  unite  dorsally,  so  that  they 
form  a  series  of  three-tined  forks. 

The  usual  number  of  horizontal  connecting  bars  pass  across  the 
tongue  bar  from  one  primary  to  the  next.  Dorsally  the  processes 


AN  UNDESCRIBED  A  CRANIATE.  229 

of  the  primary  rods  called  by  Spengel(3O)  the  "  Biigelstucke  "  are 
very  large  and  prominent ;  ventrally,  however,  the  endostylar  plates 
could  not  be  demonstrated  by  maceration  or  by  section.  Such  sec- 
tions give  the  usual  marked  difference  between  the  primary  and 
secondary  bars,  but  on  account  of  their  small  size  would  make 
difficult  any  attempt  to  trace  the  exact  course  of  the  blood  vessels 
as  determined  by  Lankester  (23)  or  by  Spengel  (3O). 

In  the  digestive  tract  of  this  Bahama  amphioxus  there  is  a 
marked  zone  of  small,  crowded  cells  that  take  up  stain  readily  and 
form  a  dark  band  posterior  to  the  stomach  region  as  indicated  in 
Fig.  5.  This  is  found  in  the  Florida  specimens  of  JBranchiostoma 
caribceum,  but  appears  not  to  have  been  noticed  in  the  European 
Amphioxus. 

The  atrial  chamber  has  the  usual  longitudinal,  ventral  ridges 
that  have  been  regarded  as  of  excretory  function,  but  a  long  search 
for  the  nephridial  tubules  found  by  Boveri(3l)  was  without  suc- 
cess, probably  owing  to  the  small  size  of  the  specimens  and  the 
distortion  due  to  preservation.  The  live  specimens  were  not  ex- 
amined for  this  purpose.  Surface  preparations  of  preserved  speci- 
mens of  the  Florida  B.  caribceum  showed  nephridia  like  those 
obtained  by  Boveri  by  this  method,  but  none  were  made  out  in  the 
small  Bahama  animals.  This  atrial  chamber  differs  from  that  of 
European  forms  in  the  extent  of  its  posterior  portion.  Thus  while 
Lankester  (23)  finds  a  single  pouch  running  back  of  the  atriopore 
"as  far  back  as  the  anus  "  there  are  here  two  short  pouches,  the 
right  longer  than  the  left,  that  seem  to  have  pushed  themselves 
back  on  either  side  of  the  atrial  outlet  and  then,  very  soon,  stopped 
growing.  Both  are  shown  in  Figure  15,  which  is  posterior  to  the 
base  of  the  atrioporal  spout,  though  showing  its  tip  ;  further  back 
Figure  21  shows  no  representative  of  the  atrium. 

In  the  Florida  B.  caribceum  there  is  a  large  post-atrioporal 
pouch  on  the  right,  but  it  does  not  reach  as  far  as  to  the  anus. 

In  the  youngest  individuals  taken,  the  floor  of  the  atrium  is  but 
imperfectly  formed,  the  two  sub-atrial  ridges  being  incompletely 
fused  on  the  median,  ventral  line. 

Here  there  is  an   interesting   segmented    arrangement  of  the 
muscle  fibers  such  as  has  not  been  noticed  before,  I  believe.     The 
transverse  muscle  of  the  atrial  floor  (Fig.  14)  begins  as  a  series  of 
2 


230  E.  A.  ANDREWS. 

fibers  in  each  sub-atrial  ridge  before  they  unite ;  there  is  thus  a 
double  series  of  transverse  fibers  that  subsequently  unite  with  one 
another  across  the  middle  line.  In  each  half  of  the  series,  on  the 
right  and  on  the  left,  the  fibers  have  the  peculiar  grouping  seen  in 
Figure  16.  There  are  three  or  four  groups  for  each  myotome,  each 
group  being  due  to  a  special  centre  of  growth  about  which  the 
fibers  are  arranged  in  pairs  and  become  gradually  longer  as  they 
adjoin  the  other  groups.  Eventually  all  the  fibers  seem  to  become 
of  equal  length  so  that  this  segmentation  is  obliterated. 

The  agreement  of  the  groups  upon  opposite  sides  of  the  median 
line  is  also  noticeable  as  a  marked  case  of  bilateral  symmetry  in 
the  arrangement  of  individual  cells  upon  disconnected,  opposite 
sides  of  the  body. 

No  thorough  examination  of  the  nervous  system  was  attempted, 
but  it  seems  to  present  no  marked  difference  from  the  state  of  things 
found  in  the  common  amphioxus.  There  are  dorsal  and  ventral 
nerves  and  amongst  the  former  a  large  one,  seen  in  Fig.  10,  that 
arises  from  the  posterior  part  of  the  brain,  branches  freely  and  is 
distributed  to  the  anterior  part  of  the  median  fin  where  there  seem 
to  be  terminal  organs  in  the  living  specimen.  Two  slender  nerves 
continued  from  the  anterior  end  of  the  brain,  along  the  notochord 
are  sometimes  seen  to  have  a  hollowed  out  b?«e  which  may  be  an 
indication  of  what  Ayres(34)  has  described  as  optic  diverticula  or 
lobes  in  the  common  lancelet,  which,  however,  seem  here  to  be  rather 
the  results  of  distortion  in  preparation  than  normal  conditions. 

The  ventricle  of  the  brain  has  in  longitudinal  median  section 
very  much  the  form  and  proportion  represented  by  Kiipffer(33), 
Figs.  21-22,  but  the  posterior  ventral  diverticulum  could  not  be 
recognized  as  a  cavity  though  indicated  by  a  non-nucleated, 
clearer  region. 

In  transverse  sections  we  have  successively  the  appearances  seen 
in  Figs.  7,  8,  9,  which  represent  the  ventricle  at  its  anterior,  middle 
and  posterior  portions  with  the  relative  size  of  lumen  and  wall. 

The  pigment  spot  at  the  anterior  end  of  the  brain  presents  nothing 
to  suggest  that  it  is  in  any  sense  an  eye.  It  is  not  placed  exactly 
as  in  the  above  figures  of  Kiipffer  but  forms  a  terminal  cap-shaped 
deposit  in  the  conical  tip  of  the  brain,  is  a  collection  of  pigment 
in  the  conical  tip  of  the  ventricle  wall  and  is  thus  cut  as  a  ring  of 


AN  UNDESCRIBED  ACRANIATE.  231 

pigment  in  a  few,  very  thin,  sections  immediately  posterior  to  the 
extreme  tip  of  the  ventricle,  Fig.  7. 

As  far  as  could  be  observed  in  surface  views  of  both  living  and 
preserved  specimens  and  in  transverse  and  longitudinal  sections  of 
both  young  and  adults  no  anterior  neuropore  or  "  nasal  pit"  exists, 
nor  any  such  connection  of  the  anterior  part  of  the  brain  with  the 
epidermis. 

The  pigment  spots  of  the  neural  tube  are  very  conspicuous  in 
life  and  in  sections  as  large  cap-shaped  masses  about  individual 
ganglion  cells  of  the  ventral  part  of  the  cord  near  the  base  of  the 
median  fissure  or  canal. 

The  spots  begin  a  short  distance  posterior  to  the  brain  and  soon 
become  more  crowded  to  form  a  series,  on  each  side,  that  ends  pos- 
teriorly before  the  caudal  process  is  reached.  There  is  throughout 
a  disposition  to  aggregation  in  linear  groups  suggesting  a  meta- 
meric  arrangement,  but  the  short  lines  of  pigment  spots  are  not 
actually  arranged  with  reference  to  the  myo tomes. 

This  pigment  is  very  resistant,  as  attempts  to  remove  it  in 
Grenacher's  depigmenting  liquid  were  not  successful  after  many 
days'  immersion. 

In  summarizing  the  above  account  of  the  Bahama  amphioxus, 
we  find  thdt  its  peculiar  structures,  asymmetry  of  the  reproductive 
organs  and  great  extension  of  the  tail  fin,  do  not  throw  light  upon 
the  morphology  of  the  acraniates,  but  are  such  characters  as  may 
be  explained  as  secondary  departures  from  a  type  more  like  the 
common  European  form.  Thus  the  lack  of  the  left  gonads  is  no 
doubt  a  loss  of  what  was  at  one  time  present.  The  extension  of 
the  tail  is  also  a  secondary  feature ;  for  we  will  see  later  that  the 
actual  number  of  myotomes  has  not  been  decreased,  on  the  con- 
trary there  are  66  here  as  compared  with  61  in  the  European 
lancelet,  so  that  we  have  no  ground  for  supposing  that  the  caudal 
process  was  once  accompanied  by  myotomes.  It  is  rather  a  pos- 
terior outgrowth  of  use  in  swimming,  a  true  caudal  process.  Yet 
the  presence  of  the  neural  tube  in  this  non-muscular  region  does 
suggest  the  former  existence  of  muscles;  on  the  other  hand  the 
extension  of  the  brain  beyond  the  anterior  myotomes  (Fig.  10) 
furnishes  evidence  as  to  the  possibility  of  nerve  tube  and  notochord 
extending  out  together  into  new  terminal  structures. 


232  E.  A.  ANDHEWS, 

Both  the  character  of  the  fins  and  the  diminution  in  bulk  of  the 
gonads,  by  loss  of  one  series,  may  be  explained  on  the  assumption 
that  they  favor  more  active  locomotion  outside  the  sand.  We  have 
evidence  that  this  species  is,  to  some  extent,  free-swimming  in  habit. 

In  order  to  determine  what  taxonomic  value  should  be  attached 
to  the  anatomical  features  of  this  Bahama  lancelet  it  will  be  neces- 
sary to  review  our  knowledge  of  known  Acraniates  as  far  as  it 
concerns  the  systematic  work  upon  members  of  the  group  and  the 
closely  associated  facts  of  geographical  distribution. 

HISTORICAL. 

As  is  well  known  the  first  recorded  account  of  Amphioxus  was 
that  of  Pallas  (1),  who  in  1774  described  a  preserved  specimen  that 
came  from  the  Cornish  coast.  Though  the  fish-like  characters  of 
this  undoubted  Amphioxus  were  recognized  by  Pallas  ("  quodque 
prima  facie  referet  Piscem  Leptocephalum  Gronovii ")  it  was  de- 
scribed and  figured  as  a  mollusc,  Limax  lanceolatus. 

This  error  was  corrected  by  Costa  (2)  who  more  than  half  a  century 
later  re-discovered  the  animal,  on  the  shores  of  the  Mediterranean, 
and  misled  by  the  gill-like  appearance  of  the  pre-oral  cirri,  named 
it  Branchiostoma-  lubrieum.  There  seems  to  be  no  doubt  that  this 
account  was  published  in  1834,  though  in  a  paper  so  difficult  of 
access  that  it  is  chiefly  the  author's  statements  made  in  the  two 
complete,  illustrated  descriptions  (3)  of  1838  and  1843  that  we  rely 
on  in  selecting  this  name  Branchiostoma  as  preferable  to  the  one 
commonly  used,  Amphioxus. 

This  latter  was  given  in  1836  by  Yarrell  (4),  who  included  in  his 
"British  Fishes"  an  illustrated  account  of  a  single  specimen  taken 
by  Mr.  Couch,  at  Polperro  on  the  Mediterranean,  where  it  hap- 
pened to  be  lying  with  its  tail  protruding  from  under  a  stone. 

Not  knowing  the  work  of  Costa,  though  acquainted  with  the 
description  of  Pallas,  Yarrell  invented  the  name  Amphioxus  lance- 
olatus  under  which  the  animal  soon  became  an  object  of  much 
interest  and  subject  of  many  anatomical  investigations. 

The  older  generic  term  was  used  again  by  J.  E.  Gray  (5),  in  de- 
scription of  a  new  species  B.  Beleheri  from  Borneo.  This  was 
obtained  at  the  mouth  of  the  river  Lundu  by  Capt.  Belcher  of  H. 


AN  UNDESCRIBED  ACRANIATE.  233 

M.S."  Samarang  "  and  "  as  what  appears  to  be  a  new  species  of 
Lancelet,"  is  described  in  a  rather  vague  and  unsatisfactory  way 
from  a  single  specimen.  Another  was  sent  to  Dr.  Clarke,  R.  N., 
for  anatomical  study,  which  appears  never  to  have  been  made 
public. 

Moreover  the  author  compared  this  new  form  with  specimens 
from  Cornwall  and  from  the  Mediterranean  and  concluded  they 
were  all  three  different  species.  This  opinion  was  maintained 
again  in  the  subsequent  Catalogue  of  the  British  Museum  (6)  where 
Gray  calls  the  Naples  form  B.  lubricum,  that  from  Borneo  B. 
Belcheri  and  those  from  Polperro  and  S.  W.  England  as  well  B. 
lanceolatum. 

In  the  following  year  Sundewall  (7)  added  to  the  knowledge  of 
the  group  by  his  description  of  the  specimens  in  the  Museum  of 
Stockholm.  Amongst  these  he  distinguished  a  new  species  A. 
elongatus,  sent  by  Capt.  Warngren  from  Chinchaoarna,  Peru,  from 
A.  lanceolatus,  from  the  German  Ocean  as  well  as  from  the  coast 
of  Cornwall.  He  included  Gray's  Borneo  species  in  the  genus 
Amphioxus,  as  A.  Belcheri. 

Soon  afterwards  (8)  he  recast  these  descriptions  and,  for  the  first 
time,  introduced  the  counting  of  the  myotomes,  or  the  muscle- 
segments,  as  a  means  of  distinguishing  species  of  Acraniata,  counting 
not  only  the  entire  number  of  segments  but  also  the  number  anterior 
to  the  atriopore,  between  that  and  the  anus  and  posterior  to  the  anus, 
thus  defining  the  relative  positions  of  these  important  structures. 

Branchiostoma  lanceolatum  (as  he  now  calls  it)  has  36  -\- 14  -{-  11 
=  61  myotomes  in  specimens  from  Northern  Europe.  B.  elon- 
gatum,  from  Peru,  49  -j-  18  +  12  =  79,  while  a  new  form,  B. 
caribceum,  found  at  St.  Thomas,  at  Rio  de  Janeiro  and  at  the 
mouth  of  the  Plata  has  37  -f  14  -f  9  =  60. 

The  four  forms  thus  far  described  were  not,  however,  regarded, 
generally,  as  specifically  distinct.  Thus  Guenther  (9)  in  1870  in 
his  catalogue  of  the  specimens  in  the  British  Museum  included  all 
known  forms  under  the  single  species  B.  lanceolatum. 

However,  in  1876  some  new  specimens  were  brought  from 
Moreton  Bay,  Peale  Sound,  Northeast  Australia,  by  Captain 
Schleinitz  of  S.  H.  S.  Gazelle  and  described  by  Peters  (11)  as 
generically  different  from  all  known  forms.  As  far  as  could  be 


234  E.  A.  ANDREWS. 

determined  from  alcoholic  specimens,  the  anatomy  of  this  new 
Epigonichthys  cultellus  was  the  same  as  in  Branchiostoma.  No 
enumeration  of  the  muscle  segments  was  made,  but  the  character 
of  fins  and  the  apparent  median  position  of  the  anus  were  regarded 
as  of  generic  value. 

Subsequently  Guenther  (1O),  in  the  only  complete  comparison  of 
all  known  forms  of  Amphioxus  that  has  thus  far  been  attempted, 
was  able  to  examine  specimens  of  this  new  genus  brought  from 
Thursday  Island,  Australia,  by  Dr.  Copinger.  Comparing  these 
with  other  Acraniata  he  referred  them  back  to  the  genus  Branchi- 
ostoma. 

Moreover,  Guenther  now  regarded  the  others  as  specifically 
distinct,  so  that  in  this  list  of  the  Acraniates  in  the  British  Museum 
we  find  the  above  form  appearing  as  B.  cultellum  then  B.  lanceo- 
latum  from  Europe  and  from  the  Atlantic  Coast  of  North  America, 
B.  elongatum  from  Peru  (on  the  authority  of  Sundevall),  B.  Bel- 
cheri  of  Gray,  represented  also  by  new  specimens  brought  by  Dr. 
Copinger  from  Prince  of  Wales  Island,  Torres  Straits,  and  finally 
B.  caribceum,  which  Van  Beneden  got  in  large  numbers  at  the 
Bay  of  Botafago  and  which  furnished  the  material  for  Moreau's 
study  of  the  neural  cord  (possibly  this  is  the  same  as  Amphioxus 
Mulleri  of  Kroyer's  MSS.). 

In  addition  to  these  previously  known  forms  this  revision  adds 
a  new  one,  B.  bassanum,  from  Bass  Straits ;  this  was  formerly 
regarded  by  Guenther  as  B.  lanceolatum.  Of  these  six  species 
five  are  represented  by  specimens  in  the  British  Museum. 

About  this  same  date,  1884  or  '85,  as  my  friend  Dr.  S.  Watase 
informs  me,  Professor  Matsubara  of  the  Medical  Department  of 
Tokio  University  read  to  the  Zoological  Society  of  Tokio  an  account 
of  an  Amphioxus  found  at  the  island  of  Kinshin,  in  the  western 
part  of  Japan. 

Whether  this  is  a  new  species  or  not  remains  to  be  seen. 

Earlier  than  that,  in  the  winter  of  1877-8,  as  appears  from  a 
brief  note  by  Professor  Brooks  (19),  an  assistant  in  the  Smithsonian 
Institution  found  some  sort  of  Amphioxus  at  the  Bermuda  Islands. 

The  knowledge  of  the  distribution  of  Sundevall's  Branchiostoma 
caribceum  was  extended  in  1891  by  the  discovery  of  small  minia- 
ture specimens  swimming  at  the  mouth  of  Kingston  Harbor, 


AN  UNDESGEIBED  A  CRANIATE.  235 

Jamaica.  These  specimens  were  taken  by  the  Johns  Hopkins 
Marine  Laboratory  and  merely  mentioned  as  Amphioxus  (21),  but 
subsequent  examination  has  proved  their  identity  with  the  forms 
previously  known  from  St.  Thomas,  South  America  and  the 
Southern  United  States. 

As  early  as  1887  the  same  Laboratory  while  at  Nassau,  N.  P., 
obtained  miniature  swimming  forms  in  the  harbor.  These  were 
taken  again  by  us  in  July  of  1892  at  the  same  place,  and  proved 
to  be  immature  specimens  of  what  we  will  call  Asymmetron  lucay- 
anum,  so  that  we  may  regard  this  form  as  probably  occurring  all 
through  the  Bahama  Islands. 

Meanwhile  there  had  appeared  brief  mention  of  the  occurrence 
of  Acraniates  at  various  points  upon  the  coast  of  North  America. 

Thus,  in  an  account  of  the  Zoology  of  California  (12)  published  in 
1868,  J.  G.  Cooper  mentions  the  occurrence  of  Branchiostoma — f 
found  in  the  sand  at  San  Diego,  California,  and  gives  a  popularized 
characterization  that  leaves  no  doubt  as  to  the  acraniate  character 
of  the  creature.  From  the  notice  of  Gill  (13)  it  appears  that  these 
Californian  lancelets  were  dredged  at  a  depth  of  ten  fathoms,  and 
that  only  three  specimens  were  found.  One  of  these  is  now  in  the 
collection  of  the  Smithsonian  Institution,  labelled  E.  californiensis. 
As  this  and  many  others  from  the  same  locality  have  an  arrange- 
ment of  myotomes  unlike  that  of  described  species,  we  may  con- 
clude that  it  is  specifically  distinct  though  it  has  been  referred  to 
as  B.  lanceolatum,  by  Jordan  and  Gilbert  (14),  who  had,  however, 
not  seen  the  specimens,  and  regarded  (15)  all  American  forms  as 
not  specifically  distinct  from  the  European,  as  far  as  had  been 
proven. 

On  the  Atlantic  coast  Coues  and  Yarrow  (16)  dredged  a  dozen  or 
more  specimens  on  Bird  Shoal,  Beaufort,  N.  C.  They  identified 
these  as  JBranchiostoma  caribceum.  This  discovery  was,  however, 
spoken  of  by  Jordan  and  Gilbert  in  their  list  of  Beaufort  Fishes  (17) 
under  the  name  Amphioxus  caribceus,  though  later,  as  above  men- 
tioned, all  American  forms  were  regarded  as  undistinguished  from 
the  European. 

At  the  same  place  Amphioxus  was  collected  by  members  of  the 
Johns  Hopkins  University  in  1880-1-2-4-5. 


236  E.  A.  ANDREWS. 

They  also  found  adult  and  larval  forms  in  1878,  by  dredging 
in  water  12  to  15  feet  deep  near  Ft.  Wool,  at  the  mouth  of  the 
Chesapeake. 

Larval  forms  were  taken  at  the  surface  in  July  and  August. 
These  were  figured  and  described  by  Rice(18)  as  AmpUoxus  lanceo- 
latus. 

From  his  statement  it  .appears  that  one  specimen  had  been  pre- 
viously found  upon  the  Eastern  Shore  of  Virginia  by  Mr.  P.  K. 
Uhler,  and  that  it  was  then  known  that  Amphioxus  had  previously 
been  found  in  Florida  as  well. 

Yet  the  first  published  notice  of  the  occurrence  of  Acraniata  in 
Florida  seems  to  be  that  of  A.  A.  Wright  (2O)  who  obtained  large 
numbers  at  Port  Tampa  in  March  1890.  Its  previous  discovery 
in  Florida  rests  upon  the  above  statement  of  Kice  and  upon  the 
presence  of  specimens  in  the  Smithsonian  Museum. 

Acting  upon  information  kindly  furnished  by  Prof.  Wright, 
members  of  the  Johns  Hopkins  Laboratory  obtained  large  numbers 
of  adult  and  larval  Branckiostoma  caribceum  at  Port  Tampa  in 
June  1892,  which  enables  us  to  extend  the  distribution  of  this 
species  as  will  be  seen  in  the  summary  of  geographical  distribution. 

From  the  above  review  it  will  be  seen  that  there  is  but  one  genus 
of  Acraniates,  Branchiostoma,  and  that  the  various  species  from 
different  parts  of  the  world  have  been  distinguished  by  the  only 
marked  differential  characters  seen  in  alcoholic  specimens;  the 
number  and  arrangement  of  the  myotomes.  Lankester  (23)  leaves 
the  question  as  to  the  fixity  of  these  numerical  characters,  an  open 
one.  So  great  is  the  difficulty  of  accurate  counting,  where  the 
terminal  myotomes  may  be  very  small  and  vaguely  demarked  in 
preserved  specimens,  that  we  do  not  know  the  limits  of  variation 
in  any  one  species.  Successive  counts  of  one  specimen  of  B. 
caribceum  have  given  me  such  numbers  as  35.  14.  9;  35.  13.  10 
and  35. 15.  9 ;  for  the  anal  and  atrial  openings  are  also  not  precisely 
localizable  in  preserved  specimens. 

In  the  first  appendix  to  this  paper  I  have  given  all  the  enume- 
rations of  myotomes  that  could  be  found  in  the  systematic  literature 
and  in  addition  a  considerable  number  made  upon  specimens  in  the 
Smithsonian  Institution  and  elsewhere.  From  a  consideration  of 


AN  UNDESCRIBED  A  CRANIATE.  237 

these,  there  is  no  doubt,  I  think,  that  such  enumerations  may  be 
relied  upon  as  giving  safe  specific  criteria  though  they  should  not 
by  any  means  be  the  only  ones,  if  live  specimens  can  be  observed. 
This  in  spite  of  the  great  difficulty  in  making  accurate  counts  and 
allowing  for  the  probable,  slight  variations  within  the  species. 
Until  the  various  forms  can  be  monographed  from  a  study  of  living 
specimens  such  characters  will  be  most  useful.1 

Admitting  that  the  number  and  arrangement  of  the  myotomes 
furnish  criteria  of  specific  value  in  the  group  Acraniata,  we  must 
concede  that  such  peculiarities  of  the  fins  and  reproductive  organs 
as  we  have  found  in  the  Bahama  Amphioxus  are  of  at  least  generic 
value  and  justify  the  establishment  of  a  new  genus  to  be  charac- 
terized as  follows : 

Asymmetron  g.  n. 2 

Gonads  present  only  upon  the  right  side. 

Ventral  fin  with  no  fin  rays  or  successive  fin-ray  chambers.  A 
long  caudal  process. 

The  only  known  species,  Asymmetron  lucayanum*  may  be  charac- 
terized as  follows  : 

Right  metapleuron  continuous  with  the  median  ventral  fin,  which 
passes  to  the  right  of  the  anus.  Pre-oral  hood  extensive,  the  cirri 
united  by  the  membrane  throughout  the  greater  part  of  their  length 
and  smooth,  without  sensory  papilla.  Gonads  on  the  right  29,  ex- 
tending from  the  15th  to  the  43d  myotomes  inclusive.  Myotome 
formula  44  .  9  .  13  =  65.  Length  13  mm.  "Olfactory  pit"  ap- 
parently absent ;  nephridia  and  brown  canals  not  demonstrated. 

Adults  and  young  swimming  at  surface  in  the  evening 'in  June 
and  July  at  Bernini  and  Nassau,  Bahamas.  Also  taken  buried  in 
the  calcareous  sand. 

With  this  addition  we  may  form  the  following  summary  of  our 
knowledge  of  the  classification  of  the  group  Acraniata. 

1  For  the  aid  of  any  who  may  wish  to  know  of  the  existence  of  preserved  speci- 
mens, a  list  of  those  in  the  Smithsonian  Museum  is  given  in  Appendix  II. 

2  a-sv/u/ufrpos,  077  =  wanting  symmetry. 

3  From  the  Lucayas;  the  islands  discovered  by  Columbus  in  1492,  now  the 
Bahamas. 


238  E.  A.  ANDREWS. 


ACRANIATA. 

Genus  BRANCHIOSTOMA.     Gonads  present  on  both  sides;  ventral 
fin  with  fin-rays  ;  no  caudal  process. 

1.  B.  lanceolatum:  formula  36  .  14  .  12  =  61,  length  37  mm.    Dis- 

tribution, Scandinavia,  England,  Mediterranean,  Chesapeake 
Bay?    Fiji  Islands? 

2.  B.  caribceum :  formula  35  . 14  .  9  =  58,  length  43  mm.    Distri- 

bution, Mouth  of  La  Plata,  Brazil,  St.  Thomas,  Jamaica, 
Tampa  Bay  and  Gulf  of  Mexico,  Beaufort,  N.  C. 

3.  B.  cultellum  .-1  formula  32  .  11  .  10  =  52,  length  23  mm.    Distri- 

bution, Moreton  Bay  and  Thursday  Island,  Australia. 

4.  B.  bassanum:  formula  44  . 14  .  17  =  75,  length .    Distri- 

bution, Bass  Straits,  Australia. 

5.  B.  belcheri:  formula  37  . 14  . 14  =  65,  length  65  mm.     Distri- 

bution, Borneo  and  Torres  Straits,  Australia. 

6.  B.  elongatum:  formula  49  .  18  . 12  =  79,  length  60  mm.     Dis- 

tribution, Chinchaoarna,  Peru. 

7.  B.  Calif orniense:  formula  44  . 16  .  9  =  68,  length  70mm.    Dis- 

tribution, San  Diego,  California. 

Genus  ASYMMETRON  ;  Gonads  present  only  on  right ;  ventral  fin 
with  no  fin-rays ;  a  long  caudal  process. 

8.  A.  lucayanum:  formula  44  .  9  .  13  =  66,  length  13  mm.    Distri- 

bution, Bimini  and  Nassau  Harbor,  Bahamas. 
In  addition  to  the  species  enumerated  above  there  are  records 
of  lancelets  found  in  other  regions  that  extend  the  area  of  geo- 
graphical distribution  and  may  modify  our  conception  of  the  num- 
ber of  specific  forms  when  all  these  specimens  shall  be  re-studied. 
At  present,  then,  the  geographical  distribution  of  the  Acraniata  may 
be  summarized  as  follows  : 

EUROPE.     Scandinavian,  British,  and  Italian  Coasts :  (1)  B.  lan- 
ceolatum. 

ASIA.     Borneo:   (1)  B.  Belcheri.     Japan:   (2) ?     (3) 

Ceylon; — ? 

1  Mr.  Arthur  Willey  of  Columbia  College  informs  me  that  he  finds  only  right 
gonads  in  this  species ;  so  I  judge  it  should  be  referred  to  the  genus  Asymmetron, 
in  a  future  revision  of  the  Acraniata. 


AN  UNDESCRIBED  A  CRANIATE. 


239 


AUSTEALASIA.  North  Australia:  (1)  B.  cultellum  and  B.  Belcheri. 
East  Australia:  (1)  B.  cultellum.  South  Australia:  (3)  B. 
bassanum.  Fiji  Islands  :  (4)  B.  lanceolatum  f  (Rohon  (22) 
quoting  C.  Hesse  of  Hamburg.) 

AMERICA.  Pacific  Coast:  (1)  B.  elongatum,  Peru;  and  (2)  B. 
Californiensej  California.  Atlantic  Coast :  (3)  B.  caribceum, 
South  America  and  Southern  United  States ;  and  (5)  B.  lance- 
olatum ?  mouth  of  Chesapeake  Bay.  West  Indies :  (3)  B. 
caribceum,  Antilles ;  and  (4)  A.  lucayanum,  Bahamas.  Ber- 
mudas : ? 


APPENDIX  I. 

(Formulas  marked  *  were  determined  more  accurately  than  others.) 
Branchiosloma  lanceolatum. 


36. 
35. 

14. 
12. 

11. 
12. 

61. 
59. 

mm. 
23-44.        Northern  Europe  :  Sundevall  (s). 
Polperro                 :  Giinther  (10). 

34. 
35. 

13. 
12. 

13. 
13. 

60. 
60. 

Naples 

35. 

15. 

10. 

61. 

Naples                    :  Lankester  (23  ). 

35. 

14. 

13. 

62. 

«                                 » 

35. 

14. 

12. 

61. 

«                                 « 

35. 

16. 

10. 

61. 

«                                 « 

36. 

15. 

11. 

62. 

«                                               tc 

36. 

13. 

12. 

61. 

37.        Stavanger,  Norway  (Smith.  Mus.)  E.A.A. 

37. 

13. 

12. 

62. 

27                 «              tt                 it 

M 

35. 

13. 

10. 

58. 

27  ;          «         «           « 

U 

35. 

12. 

13. 

60. 

07                         "                     It                          « 

U 

36. 

13. 

12. 

61. 

37]            "          "             " 

11 

36. 

15. 

10. 

61. 

52.        Sicily  :  J.  H.  U.  Mus. 

ft 

35. 

14. 

11. 

60. 

52.            "                   " 

« 

35. 

14. 

11. 

60. 

35.        Naples  :  (Bryn  Mawr  Mus.) 

u 

36. 

14. 

11. 

61. 

38. 

It 

36. 

13. 

13. 

62. 

37. 

u 

37. 

14. 

11. 

62. 

<( 

u 

36. 

13. 

11. 

60. 

36. 

u 

it 

33. 

14. 

12. 

59. 

42. 

tt 

u 

35. 

13. 

13. 

61. 

40. 

u 

(( 

36. 

14. 

12. 

62. 

42. 

u 

u 

35. 

14. 

12. 

61. 

42. 

u 

(I 

35. 

14. 

11. 

60. 

45. 

u 

tt 

36. 

14. 

12. 

62. 

44. 

u 

ft 

36. 

14. 

11. 

61. 

40. 

it 

tl 

36. 

13. 

11. 

61. 

43. 

tt 

tt 

36. 

14. 

12. 

62. 

42. 

u 

tl 

36. 

13. 

12. 

61. 

44. 

« 

It 

35. 

14. 

13. 

62. 

37.        Italy? 

It 

35. 

14. 

12. 

59. 

34: 

tt 

240 


E.  A.  ANDREW8. 


36. 

14. 

13. 

63. 

mm. 
37. 

Italy?     (Bryn  Mawr  Mus.)           E.A.A. 

36. 

14. 

12. 

62. 

36. 

H                                             It                                                          tl 

36. 

14. 

13. 

63. 

36. 

tl                                             It                                                          tt 

35. 

13. 

12. 

60. 

36. 

tl                                             It                                                           tl 

36. 
35. 

13. 
14. 

12. 
11. 

61. 

60. 

37. 
37. 

Naples: 

37. 

13. 

13. 

63. 

39. 

tt                      tt                               u 

37. 

13. 

12. 

62. 

37. 

t                             u                                       u 

38. 

13. 

13. 

64. 

36. 

t                            It                                      it 

37. 

14. 

12. 

63. 

43. 

t                                            tt                                                           it 

35. 

13. 

12. 

60. 

40. 

t                        tl                                tt 

36. 

13. 

13. 

62. 

38. 

I                                            It                                                           U 

36. 

13. 

12. 

61. 

50. 

I                                            It                                                           U 

35. 

14. 

11. 

60. 

34. 

Naples?                "                              " 

36. 

13. 

15. 

64. 

53. 

/  Chesapeake,  Ft.  Monroe  (J.  H.  U.  Mus.) 
X     E.A.A. 

36. 

13. 

13.* 

62.* 

51. 

/  Chesapeake,  Ft.  Monroe  (  J.  H.  U.  Mus.) 
\     E.A.A. 

36. 

13. 

12. 

61. 

28. 

(  CTir^nnrnlrr                                (  T    TT    TT    Mnc  ^ 

\     E.A.A. 

37. 

13. 

11. 

61. 

34. 

Chesapeake,  Willoughby  Sandspit.  E.A.A. 

36. 

16. 

7. 

59. 

20. 

f  Chesapeake  :    4  m.  East  SewelPs  Point 
1      (Smithsonian  Mus.)  E.A.A. 

33. 

14.? 

12.? 

59. 

40. 

Ceylon  (Smith.  Mus.)  E.A.A. 

35.6 

13.6 

11.8 

61. 

38.4 

Average. 

36. 

14. 

12. 

61. 

37. 

Most  frequent. 

Branchiostoma  caribceum. 

mm. 

37. 

14. 

9. 

60. 

21-51. 

/  St.  Thomas  and  Rio  de  Janeiro  :  Sunde- 

\     vail  (s). 

37. 

14. 

9. 

60. 

37. 

13. 

9. 

59. 

J  Botaf'ago,  Janeiro  and  Mouth  of  La  Plata  : 
\     Guenther  (10). 

36. 

13. 

9. 

58. 

42. 

/  Florida,  St.  Martin's  Reef  (Smith.  Mus.) 
\     E.A.A. 

34. 

15. 

9. 

58. 

32. 

Gulf  of  Mexico  (Smith.  Mus.)  E.A.A. 

36. 

15. 

8. 

59. 

31. 

tl                                           It                                    U 

36. 

14. 

9. 

59. 

45. 

/Florida,  Port  Tampa  (J.  H.  U.  Mus.) 
I     E.A.A. 

35.  . 

14. 

9. 

58. 

/Florida,  Port  Tampa  (J.  H.  U.  Mus.) 
I     E.A.A. 

36. 

15. 

8. 

59. 

43. 

/Florida,  Port  Tampa  (J.   H.  U.  Mus.) 
I     E.A.A. 

35. 

15. 

10. 

60. 

45. 

/Florida,  Port  Tampa  (J.  H.  U.  Mus.) 
X     E.A.A. 

36. 

15. 

9. 

60. 

38. 

23r-221  gonads  (J.  H.  U.  Mus.)  E.A.A. 

35. 

14. 

8. 

57. 

30. 

' 

35. 

14. 

9. 

58. 

46. 

26  r-251  gonads               ' 

36. 

14. 

9. 

59. 

43. 

26r-*261      " 

35. 

14. 

9. 

58. 

40. 

27r-241       " 

35. 

14. 

9. 

58. 

43. 

26r-261       "                    ' 

35. 

14. 

9. 

58. 

30. 

24r-231       "                    " 

AN  UNDESGRIBED  ACRANIATE.  241 


32* 

15. 

10. 

en                                 i  x-iuiiusi,    J.  ui  t    jLaiupa.    »«j.    AJ..     »j. 

57'                     \     Knower. 

XTJ_UO.  y 

32.* 

15. 

10. 

._                      /Florida,  Port  Tampa  (J.  H.  U. 
57'                     \     Knower. 

Mus.) 

35. 

17. 

7. 

-Q                     /Florida,  Port  Tampa  (J.  H.  U. 
5y'                    \     Knower. 

Mus.) 

33. 

27* 

12. 
12. 

9. 
9. 

54.             8.5      Jamaica,  Kingston   (J.  H.  U.)   E.A.A. 

48.             8.|             "                                  "                 " 

36. 

12. 

9. 

57.           13.              "                "                 " 

u 

34.8 

14. 

8.9 

57.8         33.6      Average. 

35. 

14. 

9. 

58.           43.        Most  frequent. 

Branchiostoma  Belcheri. 

37. 

14. 

13. 

64.        Borneo                              :  Guenther  (10). 

37. 

14. 

14. 

65.        Prince  of  Wales  Islands:  Guenther  (10). 

37. 

14. 

13.5 

64.5 

Branchiostoma  cultellum. 

mm. 

32. 

10. 

10. 

52.                       Thursday  Island:  Guenther  (10). 

31. 

11. 

10. 

52.     13-23.        Moreton  Bay:  Peters  (  11  ). 

31.5 

10.5 

10. 

52. 

Branchiostoma  Calif  orniense. 

44. 

16. 

9. 

K-       f  California,  San    Diego    (Cooper's 
5/'     \     Smith.  Mus.)  E.A.A. 

type, 

44. 

13. 

9. 

£„            7r.       f  California,    San    Diego    (Smith. 
bb-           /U'     {     E.A.A. 

Mus.) 

45. 

15. 

8. 

CQ             nr.       f  California,    San    Diego    (Smith. 
68'           70'     \     E.A.A. 

Mus.) 

44. 

16. 

9. 

69            68      [  California,   San    Diego    (Smith. 

Mus.) 

43* 

16. 

9. 

«Q  j^        TA       f  California,   San    Diego    (Smith. 

OO.-p            /U.         \          T?    A     A 

(^      iii.A.A. 

Mus.) 

42. 

16. 

8. 

RA            «-       f  California,    San    Diego    (Smith. 

O^r.                     00«          \           TT*     t      A 

Mus.) 

\      E.A.A. 

43. 

16. 

8. 

RfJ             -7       /  California,    San    Diego    (Smith. 
0/<     \     E.A.A. 

Mus.) 

43.8 

15.4 

8.5 

67.3         65.3      Average. 

44. 

16. 

9. 

68.           70.        Most  frequent. 

Branchiostoma  bassanum. 

44. 

13. 

18. 

75.        Bass  Straits:  Giinther  (10). 

43. 

15. 

17. 

75.           "         " 

45. 

14. 

17. 

76. 

44.          14.         17.3       75.3      Average. 


242 


E.  A.  ANDREWS. 


Branchiostoma  elongatum. 
49.         18.         12.         79.     39-60.        Peru,  Chinchaoarna :  Sundevall  (7  and  8) 

Asymmetron  lucayanum. 


43. 
45. 

8. 
9. 

14. 
12. 

65. 
66. 

mm. 
12.5         Bahamas,  Bernini  (J.  H.  U.  Mus.)  E.A.A. 
12.5 

44. 

9. 

11. 

64. 

12. 

«             it                   ti 

It 

44. 

9. 

13. 

66. 

12.5 

it             (i                  if 

tl 

44. 

9. 

13. 

66. 

10. 

it             ti                  u 

It 

43. 

9. 

12. 

64. 

11. 

ti             it                  it 

It 

42. 

8. 

12. 

62. 

10. 

u 

u 

11 

45. 

8. 

13. 

66. 

13. 

It 

11 

u 

43. 

9. 

14. 

66. 

13. 

u 

u 

It 

42. 

9. 

13. 

65. 

9. 

tl 

It 

tl 

44. 

9. 

12. 

65. 

It 

tl 

tl 

44. 

8. 

14. 

66. 

12.5 

tl 

It 

11 

44. 

8. 

13. 

65. 

12. 

tl 

11 

u 

43. 

9. 

13. 

65. 

7.5 

11 

It 

11 

46. 

9. 

13. 

68. 

12.5 

It 

It 

tl 

44. 

9. 

12. 

65. 

13. 

tl 

tl 

u 

45. 

8. 

13. 

66. 

14. 

11 

tl 

tl 

43. 

9. 

12. 

64. 

14.5 

tl 

It 

11 

44. 

9. 

13. 

66. 

14.5 

11 

11 

u 

43. 

9. 

12. 

64. 

14.    ) 

It                    tl                            11 

11 

44. 
46. 

9. 
9. 

13. 
13. 

65. 

68. 

16.     V  dug. 
14.    J 

U                         It                                   tl 

11                    It                            It 

11 
It 

43.8 

8.7 

12.7 

65.3 

12.4      Aver 

ige. 

44. 

9. 

13. 

66. 

13.        Most 

frequent. 

APPENDIX  II. 

Catalogue  of  Specimens  of  A  mphioxus  in  the  Smithsonian  Museum, 
with  numbers  and  names  as  there  attached. 

(1):   39380.     242.     Amphioxus  lanceolatus.     One  small  specimen 

from  St.  Martin's  Reef,  Florida.     Jeff.  F.  Moser. 
(2).    43555-8.     Branchiostoma  caribceum.     18  spec,  obtained  by 

U.  S.  F.  C.  Schooner  Grampus,  dredging  at  stations  5064, 

5068,  5066,  5111,  in  1889. 
(3).    27763.   Amphioxus  lanceolatus.   About  50  small  spec,  obtained 

by  Dr.  Bessels  4  miles  east  of  SewelFs  Point,  Virginia 

(Chesapeake). 


AN  UNDESCRIBED  ACRANIATE.  243 

(4).  4372.  244.  Branchiostoma  lanceolatum.  21  very  large  speci- 
mens from  San  Diego,  California.  L.  C.  Bragg. 

(5).  39646.  242.  Branchiostoma  lanceolatum.  2  spec,  (one  macer- 
ated) from  San  Diego,  California.  H.  Hembhill. 

(6).  8407.  244.  Branchiostoma  Calif  or  niensis.  One  specimen 
from  San  Diego,  California.  Cooper. 

(7).  23020.  242.  Branchiostoma  lanceolatum.  3  spec,  from 
Stavanger,  Norway.  R.  Collett. 

(8).  22083.  242.  Branchiostoma  lanceolatum.  2  spec,  from 
Stavanger,  Norway.  R.  Collett. 

(9).  34003.  244.  Amphioxus  .  Five  soft  speci- 

mens from  Ceylon.  Dr.  Francis  Day. 


REFERENCES. 

(1).   Pallas:  Spicil  Zool.  X,  p.  19,  PL  I,  Fig  11. 
(2).   Costa :  Cenni  Zoologici,  Napoli,  1834,  p.  49. 
(3).    Costa  :  Fauna  del  Regno  di  Napoli,  Fas.  21,  1838.     Storia 
e  Natomia  del  Branchiostoma  lubrico.    Frammenti  Ana- 
tomia  Comparata,  Fas.  I,  Napoli,  1843. 
(4).    Yarrell:  British  Fishes,  1836,  p.  462. 
(5).   Gray :  Proc.  Zool.  Soc.,  1847,  pp.  35-36. 
(6).    Gray  :  Cat.  Brit.  Mus.,  Fish,  Vol.  7,  p.  150. 
(7).    Sundewall :  Ofervs.  Vet.  Akad.  Forh.,  Vol.  IX,  1852,  pp. 

147_148. 
(8).   Sundevall :  Ofervs.  Vet.  Akad.  Forh.,  Vol.  X,  1853,  pp. 

12-13. 
(9).    Guenther :  Catalogue  of  Fishes,  Brit.  Museum,  1870,  Vol. 

VIII,  p.  513. 
(10).    Guenther  :  Report  Zool.  Collec.  H.  M.  S.  Alert,  Brit.  Mus., 

1884,  pp. 
(11).    Peters :    Monatsberichte  K.  Preus.  Akad.  Wiss.,  Berlin, 

1876,  pp.  322-327,  PL  I,  5  Figs. 

(12).    Cooper  :  Nat.  Wealth  of  California.    Cronise,  1868,  p.  498. 
(13).    Gill :  Notes  on  Leptocardians.    Proc.  Nat.  Mus.,  V,  1882. 
(14).   Jordan  and  Gilbert :  Fish  of  Pac.  Coast,  U.  S.    Proc.  Nat. 
Mus.,  Vol.  IV,  1881,  p.  29. 


244  E.  A.  ANDREWS. 

(15).   Jordan  and  Gilbert :  Synopsis  Fishes  of  N.  America.     Bull. 

U.S.Nat.  Mus.,  1882,  p.  867. 
(16).    Coues  and  Yarrow :  Nat.  Hist,  of  Fort  Macon,  N.  C.    Proc. 

Phil.  Acad.  Sci.,  1877,  p.  218. 
(17).   Jordan  and  Gilbert :  Fishes  of  Beaufort  Harbor.     Proc. 

Nat.  Mus.,  Vol.  I,  1878,  p.  388. 
(18).    H.  J.  Rice:  Amphioxus.    American  Naturalist,  Vol.  XIV, 

1880,  pp.  1-19,  PL  I-II. 

(19).    Brooks :  Ann.  Report  Pres.  J.  H.  Univ.,  1878,  p.  49. 
(2O).    Wright :  Amphioxus  at  Tampa.     Amer.  Naturalist,  Vol. 

24 2,  1890,  p.  10S5. 
(21).   Andrews:  Fauna  of  Jamaica.     J.  H.  U.  Circulars,  April, 

1892,  p.  75. 
(22).    Rohon  :    Amphioxus  lanceolatus.     Denkschrift  Acad.  Wiss. 

Wien.  Math.-Nat.  Cl.  45,  1882. 
(23).    Lankester:  Amphioxus  lanceolatus.     Q.  J.  Mic.  Sci.,  29, 

1889,  p.  370. 
(24).    Weiss  :  Excretory  Tubules  in  Amphioxus.    Q.  J.  Mic.  Sci., 

31,  1890,  pp.  489-496,  PL  34-35. 

(25).    Boveri :  Bildungsstatte  der  Geschlechtsdriisen  beim  Amphi- 
oxus.    Anat.  Anz.,  VII,  No.  6,  March,  1892. 
(26).    Lankester  and  Willey  :    Atrial  Chambers  of  Amphioxus. 

Q.  J.  Mic.  Sci.,  31,"  1890. 
(27).    Willey:  Larval  Development  of  Amphioxus.     Q.  J.  Mic. 

Sci.,  32,  1891. 
(28).    Langerhans:  Anatomic  der  Amphioxus.     Archiv.  f.  Mik. 

Anat,,  XII,  1876. 
(29).    Rolph  :   Ban  des  Amphioxus.     Morphologisch.es  Jarb.,  2, 

1876. 
(3O).    Spengel :    Kiemen    des    Amphioxus.      Zool.    Jarb.,    IV, 

1891. 
(31).    Boveri:    Nierencanalchen   des    Amphioxus.      Zool.    Jarb., 

V,  1892. 

(32).    vanWijhe:  Amphioxus.    Anat.  Anz.,  VII,  Feb.,  1893. 
(33).    Kiipffer  :  Kopfe  der  Kranioten.     1893. 
(34).    Ayres  :  Cephalogenesis.     Journal  Morph.,  IV,  1891. 


AN  UNDESCRIBED  ACRANIATE.  245 


EXPLANATION  OF  PLATES. 

All  the  figures  are  reduced  from  camera  lucida  drawings  of 
Asymmetron  lucayanwn. 

PLATE  XIII. 

Figure  1.  Right  side  of  an  adult  having  45  .  8  . 14  =  67  myo- 
tomes ;  reduced  to  J-  the  diameter  of  the  original  drawing  from  the 
living  specimen. 

Figure  2.  Left  side  of  the  same  specimen ;  from  a  drawing 
made  a  day  later  than  the  above. 

Figure  3.  Left  side  of  a  preserved  immature  specimen  having 
43  .  8  .  15  =  66  myotomes  and  27  gill-slits.  The  small  ventral 
caecum  is  shown  at  c. 

Figure  4.  Left  side  of  an  opaque,  preserved  specimen  14  mm. 
long,  having  44  .  8  .  13  =  63  myotomes,  gill-slits  from  the  10th  to 
35th  myotomes  and' 28  gonads  extending  from  the  16th  to  the  43d 
myotomes.  The  lines  a-h  indicate  the  regions  of  the  transverse 
sections  shown  in  Figs.  11-15  and  21-23  of  Plate  2. 

Figure  5.  Left  side  of  one  of  the  youngest  larvae.  A  preserved 
specimen  6  ram.  long  with  22  gill-slits  and  51  .  13  =  64  myotomes. 
The  caecum  is  not  yet  formed. 

Figure  6.  Ventral  view  of  anterior  region  :  from  an  immature 
preserved  specimen  having  the  pre-oral  hood  expanded. 

Figure  7.  Transverse  section  of  brain  cut  12  //,  posterior  to 
its  anterior  tip;  showing  the  pigment  bordering  this  end  of  the 
ventricle. 

Figure  8.  A  section  of  the  same  series  40  //,  posterior  to  the  tip 
of  the  brain,  where  the  ventricle  is  at  its  widest. 

Figure  9.  From  the  same  series,  52  /JL  posterior  to  tip,  where 
the  ventricle  is  coming  rapidly  to  a  close. 

Figure  10.     Left  side  of  the  anterior  extremity  of  a  mature 
specimen  macerated  in  Haller's  liquid.     The  relative  positions  of 
lymph  spaces  and  canals  are  shown.    The  dotted  line  is  the  anterior 
limit  of  the  muscle  fibers  of  the  first  myotome. 
3 


246  E.  A.  ANDREWS. 

PLATE  XIV. 

Figure  11.  Transverse  section  of  anterior  end  of  body  near 
extreme  tip  of  notochord,  at  line  (a)  Fig.  4. 

Figure  12.  Transverse  section  at  anterior  end  of  pre-oral 
chamber,  line  (6)  Fig.  4 :  the  pre-oral  pit,  ciliated  ridge  and 
blood  vessel  are  shown  on  the  animal's  right,  the  tips  of  some 
cirri  within  the  chamber. 

Figure  13.  Transverse  section  at  the  posterior  part  of  the  pre- 
oral  chamber,  line  (c)  Fig.  4,  showing  the  right  ciliated  ridge  and 
blood  vessel  of  the  Rtiderorgan. 

Figure  14.  Transverse  section  of  the  middle  of  the  body,  at 
(d)  Fig.  4,  showing  the  position  of  the  ovary  on  the  animal's  right 
side.  The  pharyngeal  basket  and  the  lining  of  the  atrium  are 
indicated  diagrammatically. 

Figure  15.  Transverse  section  at  (e)  Fig.  4,  where  the  atrium 
is  ending  in  a  spout,  the  free  tip  of  which  is  shown.  Two  post- 
atrioporal  pouches  are  seen  within  the  coelorae. 

Figure  16.  Grouping  of  muscle  fibers  in  the  right  and  the  left 
sub-atrial  ridges  of  a  young  larva ;  from  longitudinal,  horizontal 
sections.  The  limits  of  a  myotome  are  marked  by  crosses. 

Figure  17.  Optical  longitudinal  section  of  three  dorsal  fin-rays 
and  fin-ray  spaces,  from  a  preserved  specimen  stained  alive  by 
Bismarck  brown.  Certain  large  cells  at  the  top  of  each  chamber 
and  parts  of  two  dorsal  lymph  canals  are  shown. 

Figure  18.  Right  ciliated  ridge,  pre-oral  pit  and  anterior  end 
of  pre-oral  chamber  seen  in  horizontal,  longitudinal  section. 

Figure  19.  Optical,  longitudinal  section  of  the  free  part  of  a 
pre-oral  cirrus  with  its  axial  skeletal  rod.  From  a  preserved 
specimen. 

Figure  20.  Transverse  section  of  the  anterior  union  of  the  ventral, 
metapleura-like  ridges  bounding  the  edges  of  the  pre-oral  chamber. 

Figure  21.  Transverse  just  anterior  to  anus,  at  line  (/)  Fig.  4, 
showing  the  median  fin  extending  down  from  the  right  towards  a 
median  position. 

Figure  22.  Transverse  section  at  the  anus,  (g)  Fig.  4,  with  the 
median  fin  still  on  the  right  of  the  animal. 


AN  UNDESCRIBED  ACRANIATE.  247 

Figure  23.  Transverse  section  of  the  caudal  process  near  its 
tip,  (h)  Fig.  4,  showing  existence  of  nerve  cord  and  notochord,  but 
the  absence  of  muscles. 

Figure  24.  Skeleton  of  the  pre-oral  hood,  somewhat  flattened 
out.  From  macerations  in  Haller's  liquid. 

Figure  25.  Optical,  longitudinal  section  of  the  dorsal  fin  about 
the  region  (g)  Fig.  4.  Incipient  fin-ray  spaces  and  radiating  lymph 
canals  as  seen  in  a  preserved  specimen  stained  by  Bismarck  brown 
when  alive.  Some  epidermal  cells  containing  colored  spherules  are 
shown  at  a  higher  focus. 


STUDIES  FROM  BIOL.LAB 


Fig.    1 


Fig. 


Fig.    3 


Fig. 


E.  A.  ANDREWS,  del. 


VOL.V.  PLATE  XIII. 


Mg    6 


Fig.  7 


Fig.  9 


A.  HOEN  X  CO.  Photo.  Lith. 


STUDIES  FROM  BIOL. LAB. 


Fig  11 


Fig.  16 


E.A.ANDREWS,  del. 


VOL.V.  PLATE  XIV 


fig.  14 


fig.  19 


Fig. 


A.  HOEN  5  CO.  Photo.  Lith. 


14  DAY  USE 

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